With the rapid development of display technology, more and more requirements are presented for the display apparatus. The display apparatus is being developed to be thinner, more convenient, more energy-saving, and to have finer screen, lower cost, and more functions. The stacked structure of a backlight module, a lower polarizer, an array substrate, a liquid crystal layer, a color filter substrate, and an upper polarizer in the display apparatus of related technology limits the thickness of the conventional liquid crystal display apparatus, and it is difficult to make the liquid crystal display apparatus thin. Additionally, at least 60% of the light energy is wasted by a color filter layer in the color filter substrate, and it is necessary to enhance the brightness of the backlight to meet the brightness requirement of the display apparatus, which results in increased power consumption.
Nano-grating spectroscopy enables a diffraction optical element to achieve color separation of the Fresnel diffraction field, by using interference and diffraction effects between nano-gratings. By selecting appropriate grating heights and phase distribution, three colors of red, green and blue can be separated efficiently in space. How to apply a nanometer light splitting element into a display apparatus and how to improve the color quality without substantially increasing cost are important issues in the field of liquid crystal display.